May 29, 2023

‘Very dangerous’: New maps show waves over 12m tall, highest risk of coastal flooding

Watch: Video shows Cyclone Gabrielle's predicted path and impact on NZ.

New maps show waves over 12 metres high are being whipped up to the north of New Zealand as Cyclone Gabrielle gets even closer.

Official Government update – Cyclone Gabrielle

  • Cyclone Gabrielle will impact much of the North Island with severe gales, heavy rain and very large waves forecast from today through to Tuesday.
  • This is expected to be an unprecedented and dangerous weather event. 
  • MetService has issued severe weather warnings for many parts of the North Island.
  • Keep up to date with MetService weather warnings and advice from your local Civil Defence Emergency Management Group.  
  • Adhere to all advice and instructions from authorities.
  • Cyclone Gabrielle will also exacerbate the impacts for those communities recovering from recent floods
  • Avoid travelling during severe weather, and check Waka Kotahi for road closures. 
  • Do what you can to prepare your household for the coming days.
  • Information about preparing for storms can be found at 
  • Call 111 if you feel in any danger.
  • Stay safe. Don’t take any chances.

The cyclone is approaching the country from the north on Sunday and is expected to lie just east of Northland on Monday. It’s then expected to slowly move southeast, passing very close to East Cape late on Tuesday before moving southeast near the Chatham Islands on Wednesday and Thursday.

NIWA warns coastal conditions will be very dangerous, with 5-8 metre waves likely in the northern and eastern North Island on Monday and Tuesday.

MetService said waves of nearly 11 metres have already been recorded at the Bay of Islands at 4pm on Sunday.

The area most at risk stretches on the east coast of the North Island from Cape Brett Peninsula in the Bay of Islands down as far as Tauranga. On the west coast, there are pockets of danger for harbour areas.

The size of the swell means coastal flooding and inundation are likely, with another map showing where the risk is highest. NIWA said this will be worse in low-lying areas and during high tide.

“Erosion will likely be a big issue along exposed coasts,” NIWA warned on Twitter.

“Bay of Plenty and Hawke’s Bay: waves will be very large and heading straight toward the shore.”

MetService has issued a heavy swell warning in the Wairarapa from Turakirae Head to Mataikona.

“Northeast swell rising to 4.5 metres but 5.5 metres north of Flat point Monday evening, then rising to 6.5 metres throughout on Tuesday morning,” it said.

“Easing to 5 metres Tuesday evening and 4 metres Tuesday night. Peak period 10-12 seconds.”

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